A Novel Pregnane Ester Tetraglycoside from Orthenthera viminea

Abstract

A new pregnane ester tetraglycoside designated as orthenine (1) has been isolated from the dried twigs of Orthenthera viminea. Chemical and spectroscopic evidence is consistent with the structure 12-0-cinnamoyl sarcostin 3-0-a-L-oleandropyranosyl (li-»4)-Q-a-Loleandropyranosyl (li-»4)-0-a-L-oleandropyranosyl (1>-»4)-0-3-D-cymaropyranoside for orthenine.In previous communications, we have reported the isolation and structural elucidation of four novel oligosaccharides (1-5) and pregnane ester glycosides (6,7) from the twigs of Orthenthera viminea W. & A. (Asclepiadaceae). As a continuation of studies on this plant, we are presenting here spectral and chemical evidence for the structure of a new oligoglycoside, designated as orthenine (1). RESULTS AND DISCUSSIONOrthenine (1) mp 120-124°, {a]D + 115°, C58H88019, responded positively to the Liebermann Burchardt test (8), xanthydrol (9,10) and Keller-Kiliani reactions (11), indicating it to be a steroidal glycoside of a 2-deoxy sugar residue. The presence of a vicinal diol system in the molecule was indicated by its positive reaction with NaI04. In the 'H-nmr spectrum of 1 at 400 MHz, the presence of characteristic methylene signals in the regions 2.36-2.07 (4H) and 2.02-1.80 (4H), in conjunction with four secondary methyl group doublets (J=6 Hz) at 1.35 (3H), 1.33 (6H), and 1.24 (3H) and four methoxy group singlets at 3.46, 3.45, 3-40, and 3.39, provided evidence that 1 is a tetraglycoside of 2,6-dideoxy hexoses.Mild acid (0.025 M H2S04) hydrolysis ( 12) of 1 afforded a crystalline genin 2 and a mixture of two sugars. The separated sugars 5 and 6 displayed characteristic color tests of 2-deoxy sugars and were identified as D-cymarose (13) (2,6-dideoxy-3-O-methyl-Dribohexose) and L-oleandrose (14,15) (2,6-dideoxy-3-0-methyl-L-arabinohexose) (pc and {a]D). For further characterization, 5 and 6 were oxidized with bromine water to their lactones 7 and 8, respectively, which on treatment with phenylhydrazine yielded known crystalline derivatives, i.e., D-cymaronic acid phenylhydrazide (9) (13) and Loleandronic acid phenylhydrazide (10) (14,15). On the basis of the above results, 1 was

Identification of C21 Steroidal Glycosides from Gymnema sylvestre (Retz.) and Evaluation of Their Glucose Uptake Activities

“…Four known compounds were also isolated and identified as gymnepregoside H (5), [23] deacetylkidjoladinin (6), [34] gymnepregoside G (7) [23] and gymnepregoside I (8) [35], by comparison of spectroscopic data and physicochemical properties with those reported values in the literatures.…”

“…1 H and13 C nmR data of compounds 3 and 4 (δ H in ppm, J in Hz).Compound 4 was isolated as a white powder. The molecular formula was established as C35 H 54 O 11 by HRESIMS data m/z 673.3553 [M + Na] + , (calcd for 673.3564) (Figure…”